1. Field of the Invention
The present invention relates generally to flying devices. Particularly, the present invention relates to unmanned aerodynamic vehicles (UAV). More particularly, the present invention relates to micro-unmanned aerodynamic vehicles.
2. Description of the Prior Art
Existing unmanned aerial vehicles (UAVs) have been successfully tested and utilized for outdoor aerial reconnaissance missions. Experiments have shown on numerous occasions, including operations such as Desert Storm, that UAVs often go unnoticed when flying at several thousand feet over their targets. The state of the art in optics is such that high resolution video and infrared images can be gathered unobtrusively from existing platforms.
There is a similar need for UAVs that are capable of performing close environment reconnaissance such as, for example, indoor reconnaissance missions. The requirements for a UAV to successfully perform close environment reconnaissance may include such capabilities as rapidly negotiating hallways, crawling under doors, or navigating ventilation systems in an attempt to quickly penetrate deep into a building to complete the mission. Meso-scale aerodynamic vehicles (MAV) have been proposed to fulfill such mission requirements. MAVs are generally thought of as miniature flying machines having no dimension greater than approximately 15 cm.
There is a huge difference between the world of macroscale and microscale aerodynamics. Macroscale aerodynamics, referred to as quasi-steady state aerodynamics (i.e. fixed wing airfoil), predominately depends on inertial forces to stay aloft. At the microscale, insects and other small airborne creatures, fly on an unsteady viscous sea of their own creation. They intentionally induce complex wakes and vortices in order to stay airborne. This complex form of flight is known as unsteady state aerodynamics and is exhibited in all flapping flight. Using Reynolds Numbers (a unitless number which signifies the extent of inertial forces to viscous forces), it can be quantitatively determined when steady state aerodynamics become obsolete and when flapping flight is necessary. Large airplanes range in the millions of Rey while insects range in the thousands of Rey or lower.
There have been several MAVs developed in the past. One such MAV was developed at UC Berkley. The UC Berkley MAV was a small electrically powered meso-scale-flapping device. The UC Berkley MAV included a 1.3 cm large “thorax” which translates the small linear displacement of two piezoelectric actuators into full, three-dimensional, flapping motions via a complex “four-bar” transmission system.
U.S. Pat. No. 6,082,671 (2000, Michelson) discloses an apparatus and method for multimodal electrochemical insect known as an entomopter. The entomopter is a species of a MAV. The entomopter mimics the flight characteristics of an insect by flapping wings to generate lift. The entomopter's wings are powered by a reciprocating power source. The Michelson device accomplishes the three-dimensional, flapping motion by way of a complex transmission system that incorporates a plurality of bellows that are pressurized and vented and other linkage or springs and pistons, or linkage structure with reciprocating actuator, etc.
The prior art MAVs are not true microscale vehicles but mesoscale vehicles. This is so because the prior art MAVs have fuselages (i.e. thorax) in the centimeter size range.
Therefore, what is needed is a micro-unmanned aerodynamic vehicle flapping device (μ-UAV) with full-flapping functionality (i.e. translational and rotational motion) from two-dimensional linear displacement without the use of a complex transmission system. What is also needed is a μ-UAV that is about ten times smaller than the smallest flapping vehicles currently available. What is further needed is a μ-UAV that uses MEMS-based (micro electro-mechanical system) technology. What is still further needed is a μ-UAV that requires virtually no assembly since, as scale decreases in a meso-scale device, assembly becomes more and more difficult.